As various electronic devices have increasingly had high performance in recent years, heat-generating components, such as integrated circuits (ICs), generate a large amount of heat heating a chassis of an electronic device. Further, an excessively heated IC may degrade an operating speed of the IC. FIG. 9 is a cross-sectional view of conventional electronic device 500. In electronic device 500, heat diffusion sheet 2A, such as a graphite sheet, with a high thermoconductivity is thermally connected to heat-generating component 2 mounted on substrate 1 to dissipate heat generated by the component.
PTL 1 discloses a device similar to electronic device 500.
Conventional electronic device 500 shown in FIG. 9 can address heat generation to some extent; but often has difficulty in heat dissipation for instantaneous increase of heat generation. In particular, electronic device 500 generates heat when downloading a lot of data. Such downloading does not continue for a long time. Therefore, it is important to suppress the temporary raising of a temperature due to the heat generation. Besides, the longer the time of heat generation, the higher the temperature of heat-generating component 2. It also needs to suppress the temperature. The rising of temperature increases interconnection resistance, power consumption of the device, and the usage of the battery for driving electronic device 500. Suppressing temperature rise is therefore critical.